Cancer Staging and Grading

Topic Overview

Knowing the stage and grade of a person's cancer helps doctors know what treatment to use. It also helps predict how long the person will survive or whether there is a good chance for a cure.

Staging is a process that doctors use to describe how far cancer has spread.

Grading is a process that helps predict how fast the cancer will grow and spread.

Cancer stages

In general, the stages of most cancers break down this way:

• Stage 0: Cancer hasn't spread.
• Stages I, II, and III: Cancer has grown or has spread into nearby tissues and perhaps lymph nodes. The higher the stage, the farther the cancer has spread.
• Stage IV: Cancer has spread beyond the lymph nodes into other parts of the body (metastasized).

Although there are several methods of staging, most doctors now use the TNM method. The TNM method is based on the size of the tumor (T), the spread of the cancer into nearby lymph nodes (N), and the spread of the cancer to other body parts (M, for metastasis).

TNM staging labels

T (tumor)	N (lymph nodes)	M (metastasis)
TX: Unable to measure tumor. T0:No evidence of tumor. Tis: Tumor hasn't grown into nearby tissue. T1 toT4: Tumor has grown into nearby tissue (numbers 1-4 describe how much the tumor has grown).	NX: Unable to evaluate lymph nodes. N0: No cancer found in lymph nodes. N1to N3: Cancer has spread into lymph nodes. (Numbers 1-3 are based on how many nodes are involved and how much cancer is found in them.)	M0:Cancer hasn't spread to other parts of the body. M1:Cancer has spread to other parts of the body.

Most cancers can be described using the TNM system. But certain cancers-for example, cancers of the blood, bone marrow, or brain-use other staging systems.

Tumor grades

A tumor's grade, from 1 to 4, describes how its cells look under a microscope. The more these cells look like normal cells, the lower the grade and the lower the likelihood that the cancer will spread quickly.

Tumor cells that look like normal cells are called grade 1 tumors. They usually grow slowly.

A grade 4 tumor, on the other hand, has cells that look very different from normal cells. Grade 4 tumors often grow quickly and spread rapidly.

For certain types of cancer, doctors use other grading methods. For example, in prostate cancer, the doctor gives the cancer a Gleason score. Prostate cancer cells that have a low Gleason score grow more slowly than cells that have a higher score.

Breast cancer and kidney cancer also use other grading methods.

What tests are used to find a cancer's stage and grade?

• Physical exams.For some cancers, looking at or feeling the body part involved can give doctors information about how far a cancer has advanced.
• Imaging tests. Tests that help doctors look inside the body to find tumors include:
  • X-ray.
  • MRI.
  • CT scan.
  • PET scan.
  • Ultrasound.
• Biopsy . This procedure-to collect tissue samples-can help doctors decide the stage or the grade of cancer. It can sometimes be done in the doctor's office.
• Surgery. Sometimes doctors use surgery to view the tumor as well as collect tissue samples.